For the second time in two weeks, Democratic and Republican negotiators on immigration have emerged from meeting rooms on Capitol Hill, coyly saying some variation of “we’ve made progress” or “we have a deal in principle” — or dodging the press altogether.

What lawmakers have discovered is that an agreement in principle means nothing when the principals don’t agree.

It’s been a dizzying experience for everyone in the Capitol — from leadership on down — who hasn’t the faintest idea of what the group of eight lawmakers are doing behind closed doors.

While the Senate is set to take up its bill next month that would provide for a pathway to citizenship for 11 million undocumented immigrants, the House talks have been a roller coaster of threats, unofficial statements and self-imposed deadlines.

The irony of this process is that the House’s immigration bill will never become law — it’s only a vehicle to get to a conference negotiation with the Senate. In fact, many Democrats are hoping that the House bill implodes, leaving the Senate bill as the only viable option.

Here’s where things stand: Sources familiar with the talks — and, by design, there aren’t many — say that an agreement is close enough that they will begin drafting language.

The biggest lingering issue — if the government should subsidize any health care for immigrants seeking citizenship — appears to be settled. Under a tentative deal reached Thursday, immigrants who are in the United States illegally would need to buy their own insurance, and if they accept government subsidized care, they’re out of the country. Republicans agreed to exempt emergency care.

“We’re hoping that we have a fix that conforms with, you know, some basic principles,” said Rep. Mario Diaz-Balart (R-Fla.), one of the eight negotiators. “Which is that these people that we’re dealing with — that we’re trying to deal with — do not become a public charge.”

Everything settled then?

Nope. Not even close.

Minority Leader Nancy Pelosi (D-Calif.) raised another potential concern Thursday — one involving the legislation’s trigger. Republicans have crafted a so-called trigger mechanism that shuts down the legalization program if E-Verify — an employment verification system — isn’t in place in five years.

Democrats in the negotiations had gone along with the E-Verify trigger — but not happily.

“It’s not the immigrants’ responsibility to make sure E-Verify works,” Pelosi said. “So we just have to hope E-Verify works, or else the whole deal is off. The whole arrangement is off, and millions of what we call probationary immigrants then revert to the status that is not a path to legalization.”

The problems don’t end there. Democrats are concerned that Republicans want to make the E-Verify program subject to the wild world of congressional appropriations. In other words, if someone decides that 11 million undocumented immigrants should not become citizens, they could withhold federal funds, and the process would collapse. Republicans privately say they aren’t bending on this point. If that trigger becomes an issue, the entire bill could crumble.

On the other side of the aisle, Speaker John Boehner (R-Ohio) is accusing Democrats and members of his own party of sabotaging the negotiations.

“There are people on both sides of the aisle who’ve done their best to try to undermine their ability to get to an agreement,” he said. Pressed to give names, he said, “You can go find out for yourselves, because I think you’ll figure it out.”

Boehner made more of a definitive statement later Thursday, when he, along with his top deputies in leadership and Judiciary Committee Chairman Bob Goodlatte (R-Va.), flatly said they won’t take the Senate bill as is — if it passes that chamber.

”Rather, through regular order, the House will work its will and produce its own legislation,” the House Republicans said in a statement. “Enacting policy as consequential and complex as immigration reform demands that both chambers of Congress engage in a robust debate and amendment process.”

Senate immigration negotiators had been hoping for broad majority of support in their chamber — perhaps north of 70 votes — to put pressure on the House to act on its legislation. But House Republicans have resisted that strategy, proclaiming several flaws with the bill that they believe would be dead on arrival on their side of the Capitol.

Sen. Lindsey Graham (R-S.C.), a member of the bipartisan Gang of Eight that wrote the Senate bill, said Thursday the House Republican leadership’s stance is “fine” with him.

“I just want to get a bill passed from the Senate,” Graham said. If the legislation is sent to the House, “they can do anything they want with it.”

Still, several House negotiators were publicly encouraged after Thursday afternoon’s meeting, when they kicked out staffers and talked just among the eight group members. Diaz-Balart said the lawmakers “made a lot of progress,” and Rep. Raul Labrador (R-Idaho) said that while lawmakers still need to work out the language, they were “all positive that we could move forward.”

“We are still a group, we are still working,” said Rep. Luis Gutierrez (D-Ill.). “Much has been said this week about the demise of this process. I continue to be optimistic.”

The constantly evolving state of play in the House is in sharp contrast to the methodical movement in the Senate, where a key panel cleared the sweeping Gang of Eight legislation on a 13-5 vote this week.

After going through five days of markups and a slew of amendments, the Senate Gang of Eight bill is being readied for what will almost certainly be a long and vigorous floor debate on how to revamp U.S. immigration laws.

Senate Majority Leader Harry Reid (D-Nev.) said Thursday he was talking with the Gang of Eight negotiators and Senate Judiciary Committee Chairman Patrick Leahy (D-Vt.) to determine when to bring the bill to the floor — whether immediately following the Memorial Day recess or the week after, starting June 10. No decisions have yet been made.

“I am not going to do anything to interfere with the immigration bill,” Reid said Thursday. “I’ve spent a lot of my legislative life dealing with this issue. For me, it is an extremely important issue personally. And each day that goes by, I became more convinced.”